A couple of things come to mind. you can shave overall time without any extra exertion by being organized in your transitions. Practice them. Lay out your clothes, shoes...for each transition befor they close the area. (My first sprint tri., I didn't think to have my running shoes untied. Probably cost me 45 seconds)
Practice getting off your cycle, changing shoes and running. it's amazing how heavy your legs feel the first mile or so.